Shaped spring element for a non-contact seal device

ABSTRACT

A non-contact seal assembly includes a plurality of seal shoes, a seal base and a plurality of spring elements. A first of the spring elements includes a first mount, a second mount and a spring beam. The spring beam extends a length longitudinally along a centerline from the first mount to the second mount. The spring beam includes opposing first and second surfaces. The first surface is disposed a first distance from the centerline, and the second surface is disposed a second distance from the centerline. The first distance and the second distance change as the spring beam extends longitudinally along the centerline to provide at least a portion of the spring beam with a tapered geometry. The portion of the spring beam has a longitudinal length that is at least about five percent of the length of the spring beam.

This patent application is a continuation of and claims priority to U.S.patent application Ser. No. 15/053,696 filed Feb. 25, 2016. The '696application is hereby incorporated herein by reference in its entirety.

This invention was made with Government support under Contract No.FA8650-09-D-2923 awarded by the United States Air Force. The Governmentmay have certain rights in the invention.

BACKGROUND OF THE INVENTION 1. Technical Field

This disclosure relates generally to rotational equipment and, moreparticularly, to a non-contact seal assembly for rotational equipment.

2. Background Information

Rotational equipment typically includes one or more seal assemblies forsealing gaps between rotors and stators. A typical seal assemblyincludes a seal element such as a knife edge seal that is positionedrelative to a seal land. However, such seal assemblies may besusceptible to leakage between the seal element and the seal land as aresult of asymmetric deflection between the associated rotor and stator.While non-contact seals have been developed in an effort to accommodatesuch asymmetric deflection, there is still room for improvement toprovide an improved non-contact seal.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, a non-contact sealassembly is provided that includes a plurality of seal shoes, a sealbase and a plurality of spring elements. The seal shoes are arrangedabout an axis in an annular array. The seal base circumscribes theannular array of the seal shoes. A first of the spring elements isradially between a first of the seal shoes and the seal base. The firstof the spring elements includes a first mount, a second mount and aspring beam. The first mount is connected to the first of the sealshoes. The second mount is connected to the seal base. The spring beamextends a length longitudinally along a centerline from the first mountto the second mount. The spring beam includes opposing first and secondsurfaces. The first surface is disposed a first distance from thecenterline. The second surface is disposed a second distance from thecenterline. The first distance and the second distance change as thespring beam extends longitudinally along the centerline to provide atleast a portion of the spring beam with a tapered geometry. The portionof the spring beam has a longitudinal length that is at least about fivepercent of the length of the spring beam.

According to another aspect of the present disclosure, anothernon-contact seal assembly is provided that includes a plurality of sealshoes, a seal base and a plurality of spring elements. The seal shoesare arranged about an axis in an annular array. The seal basecircumscribes the annular array of the seal shoes. A first of the springelements is radially between a first of the seal shoes and the sealbase. The first of the spring elements includes a first mount, a secondmount and a spring beam. The first mount is connected to the first ofthe seal shoes. The second mount is connected to the seal base. Thespring beam extends a length longitudinally along a centerline from thefirst mount to the second mount. The spring beam includes first andsecond surfaces. The first surface is disposed a first distance from thecenterline. The second surface is disposed a second distance from thecenterline and opposite the first surface. The first distance and thesecond distance change as the spring beam extends longitudinally alongthe centerline to provide at least a portion of the spring beam with atapered geometry. The first surface and/or the second surface is convexat least along a part of the portion of the spring beam.

According to still another aspect of the present disclosure, anothernon-contact seal assembly is provided that includes a plurality of sealshoes, a seal base and a plurality of spring elements. The seal shoesare arranged about an axis in an annular array. The seal basecircumscribes the annular array of the seal shoes. A first of the springelements is radially between a first of the seal shoes and the sealbase. The first of the spring elements includes a first mount, a secondmount and a spring beam. The first mount is connected to the first ofthe seal shoes. The second mount is connected to the seal base. Thespring beam has a length and a centerline. The length of the spring beamextends longitudinally along the centerline from the first mount to thesecond mount. The spring beam includes opposing first and secondsurfaces. In a first portion of the spring beam, the first surface andthe second surface substantially symmetrically converge towards thecenterline as the first portion of the spring beam extendslongitudinally along the centerline. The first portion of the springbeam has a longitudinal length that is equal to or greater than aboutfifteen percent of the length of the spring beam.

The portion of the spring beam may have a longitudinal length that is atleast about five percent of the length of the spring beam.

The portion of the spring beam may have a longitudinal length that isbetween about five percent and about ten percent of the length of thespring beam.

The portion of the spring beam may have a longitudinal length that isbetween about ten percent and about twenty-five percent of the length ofthe spring beam.

The portion of the spring beam may have a longitudinal length that isgreater than about twenty-five percent of the length of the spring beam.

A fillet may be included longitudinally between the portion of thespring beam and a respective one of the first and the second mounts.

The first surface may be convex at least along a part of the portion ofthe spring beam. In addition or alternatively, the second surface may beconvex at least along a part of the portion of the spring beam.

The first distance and the second distance may change, along at least apart of the portion of the spring beam, as a function of a square rootof a longitudinal distance from a longitudinal mid-point of the springbeam.

The portion of the spring beam may be a first portion of the spring beamdisposed longitudinally next to the first mount. The first distance andthe second distance may further change as the spring beam extendslongitudinally along the centerline to provide a second portion of thespring beam, disposed longitudinally next to the second mount, with atapered geometry. The second portion of the spring beam may have alongitudinal length that is at least about five percent of the length ofthe spring beam.

The longitudinal length of the first portion of the spring beam may besubstantially equal to the longitudinal length of the second portion ofthe spring beam.

An intermediate portion of the spring beam may extend longitudinallybetween the first portion and the second portion of the spring beam. Thefirst distance and/or the second distance may be substantially constantalong the intermediate portion.

The intermediate portion of the spring beam may have a longitudinallength that is between about five percent and about ten percent of thelength of the spring beam.

The intermediate portion of the spring beam may have a longitudinallength that is between about ten percent and about twenty-five percentof the length of the spring beam.

The intermediate portion of the spring beam may have a longitudinallength that is between about twenty-five percent and about fifty percentof the length of the spring beam.

The spring beam may extend radially relative to the axis between thefirst and the second surface. The tapered geometry may be or include aradial tapered geometry.

The spring beam may extend axially relative to the axis between thefirst and the second surfaces. The tapered geometry may be or include anaxial tapered geometry.

The first of the spring elements may include a second spring beamextending a length longitudinally along a second centerline from thefirst mount to the second mount. The second spring beam may includeopposing third and fourth surfaces. The third surface may be disposed athird distance from the second centerline. The fourth surface may bedisposed a fourth distance from the second centerline. The third and thefourth distances may change as the second spring beam extendslongitudinally along the second centerline to provide at least a portionof the second spring beam with a tapered geometry. The portion of thesecond spring beam may have a longitudinal length that is at least aboutfive percent of the length of the second spring beam.

A ring structure may be included and axially engaged with the seal base.A secondary seal device may be included and mounted with the ringstructure and configured to substantially seal an annular gap betweenthe ring structure and the annular array of the seal shoes.

The foregoing features and the operation of the invention will becomemore apparent in light of the following description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top half, side section illustration of an assembly for anitem of rotational equipment with a rotational axis.

FIG. 2 is a perspective general representation of a primary seal device.

FIG. 3 is a top half, side sectional illustration of a primary sealdevice.

FIG. 4 is a partial, cross sectional illustration of the primary sealdevice of FIG. 3.

FIG. 5 is a cross-sectional illustration of a portion of a primary sealdevice, which portion includes a spring beam between two mounts.

FIG. 6 is a circumferential sectional (e.g., top view) illustrationdepicting an embodiment of the spring beam of FIG. 5.

FIG. 7 is a circumferential sectional (e.g., top view) illustrationdepicting another embodiment of the spring beam of FIG. 5.

FIG. 8 is a graphical representation depicting how a portion of a springbeam may be tapered.

FIG. 9 is a partial stress diagram for a portion of another spring beam.

FIG. 10 is a partial stress diagram for a portion of a spring beamaccording to an embodiment of the present disclosure.

FIG. 11 is a side, cutaway illustration of a gas turbine engine whichmay include the assembly of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an assembly 20 for an item of rotational equipmentwith a rotational axis 22. An example of such an item of rotationalequipment is a gas turbine engine for an aircraft propulsion system, anexemplary embodiment of which is described below in further detail.However, the assembly 20 of the present disclosure is not limited tosuch an aircraft or gas turbine engine application. The assembly 20, forexample, may alternatively be configured with rotational equipment suchas an industrial gas turbine engine, a wind turbine, a water turbine orany other apparatus in which a seal is provided between a statorstructure and a rotor structure.

The assembly 20 of FIG. 1 includes a stator structure 24, a rotorstructure 26 and a seal assembly 28, which is fixed relative to thestator structure 24. This seal assembly 28 is mounted with the statorstructure 24, and configured to substantially seal an annular gap 30between the stator structure 24 and the rotor structure 26 as describedbelow in further detail.

The stator structure 24 includes a seal carrier 32. This seal carrier 32may be a discrete, unitary annular body. Alternatively, the seal carrier32 may be configured with another component/portion of the statorstructure 24. The seal carrier 32 has an inner radial seal carriersurface 34. This seal carrier surface 34 may be substantiallycylindrical, and extends circumferentially around and faces towards therotational axis 22. The seal carrier surface 34 at least partially formsa bore in the stator structure 24. This bore is sized to receive theseal assembly 28, which may be fixedly attached to the seal carrier 32by, for example, a press fit connection between the seal assembly 28 andthe seal carrier surface 34. The seal assembly 28, of course, may alsoor alternatively be fixedly attached to the seal carrier 32 using one ormore other techniques/devices.

The rotor structure 26 includes a seal land 36. This seal land 36 may bea discrete, unitary annular body. Alternatively, the seal land 36 may beconfigured with another component/portion of the rotor structure 26. Theseal land 36 has an outer radial seal land surface 38. This seal landsurface 38 may be substantially cylindrical, and extendscircumferentially around and faces away from the rotational axis 22. Theseal land surface 38 is disposed to face towards and is axially alignedwith the seal carrier surface 34. While FIG. 1 illustrates the surfaces34 and 38 with approximately equal axial lengths along the rotationalaxis 22, the seal land surface 38 may alternatively be longer or shorterthan the seal carrier surface 34 in other embodiments.

The seal assembly 28 includes a primary seal device 40 and one or moresecondary seal devices 42; e.g., 1, 2, 3 or more secondary seal devices42. The seal assembly 28 also includes one or more additional componentsfor positioning, supporting and/or mounting one or more of the sealdevices with the stator structure 24. The seal assembly 28 of FIG. 1,for example, includes a first ring structure 44 configured forpositioning, supporting and/or mounting the secondary seal devices 42relative to the primary seal device 40. This first ring structure 44 mayalso be configured for axially positioning and/or supporting a secondend surface 46 of the primary seal device 40 relative to the statorstructure 24. The seal assembly 28 of FIG. 1 also includes a second ringstructure 48 (e.g., a scalloped support ring) configured for axiallypositioning and/or supporting a first end surface 50 of the primary sealdevice 40 relative to the stator structure 24. However, the second ringstructure 48 may be omitted where, for example, the first end surface 50of the primary seal device 40 may be abutted against anothercomponent/portion of the stator structure 24 (e.g., an annular orcastellated shoulder) or otherwise axially positioned/secured with thestator structure 24.

Referring to FIG. 2, the primary seal device 40 is configured as anannular non-contact seal device and, more particularly, a hydrostaticnon-contact seal device. An example of such a hydrostatic non-contactseal device is a HALO™ type seal; however, the primary seal device 40 ofthe present disclosure is not limited to the foregoing exemplaryhydrostatic non-contact seal device.

Referring to FIGS. 3 and 4, the primary seal device 40 includes a sealbase 52, a plurality of seal shoes 54 and a plurality of spring elements56. The seal base 52 is configured as an annular full hoop body, whichextends circumferentially around the rotational axis 22. The seal base52 is configured to circumscribe the seal shoes 54 as well as the springelements 56. The seal base 52 extends axially along the rotational axis22 between and forms the second end surface 46 and the first end surface50. The seal base 52 extends radially between an inner radial base side58 and an outer radial base side 60, which radially engages (e.g., ispress fit against) the stator structure 24 and, more particularly, theseal carrier surface 34 (see FIG. 1).

Referring to FIG. 2, the seal shoes 54 are configured as arcuate bodiesarranged circumferentially about the rotational axis 22 in an annulararray. This annular array of the seal shoes 54 extends circumferentiallyaround the rotational axis 22, thereby forming an inner bore at an innerradial side 62 of the primary seal device 40. As best seen in FIG. 1,the inner bore is sized to receive the seal land 36, where the rotorstructure 26 projects axially through (or into) the inner bore formed bythe seal shoes 54.

Referring to FIG. 4, each of the seal shoes 54 extends radially from theinner radial side 62 of the primary seal device 40 to an outer radialsurface 64 of that seal shoe 54. Each of the seal shoes 54 extendscircumferentially around the rotational axis 22 between opposing firstand second circumferential sides 66 and 68 of that seal shoe 54.

Referring to FIG. 3, each of the seal shoes 54 extends axially along therotational axis 22 between a first shoe end 70 and a second shoe end 72.The first shoe end 70 may be axially offset from and project axiallyaway from the first end surface 50. The second shoe end 72 may beaxially offset from and project axially away from the second end surface46. The seal shoes 54 of the present disclosure, however, are notlimited to such exemplary relationships.

Referring to FIG. 3, each of the seal shoes 54 includes an arcuate endsurface 74 generally at (e.g., on, adjacent or proximate) the secondshoe end 72. In the array (see FIG. 2), these arcuate end surfaces 74collectively form a generally annular (but circumferentially segmented)end surface 76 configured for sealingly engaging with the secondary sealdevices 42; see FIG. 1. The seal shoes 54 of the present disclosure,however, are not limited to the foregoing exemplary configuration.

Referring to FIGS. 3 and 4, each of the seal shoes 54 includes one ormore arcuate protrusions 78, which collectively form one or more (e.g.,a plurality of axially spaced) generally annular (e.g.,circumferentially segmented) ribs 80 at the inner radial side 62. Distalinner radial ends of one or more of these ribs 80 are configured to bearranged in close proximity with (but not touch) and thereby sealinglyengage the seal land surface 38 in a non-contact manner (see FIG. 1),where the rotor structure 26 project axially through (or into) the innerbore formed by the seal shoes 54. The ribs 80 therefore are configured,generally speaking, as non-contact knife edge seal elements.

Referring to FIG. 2, the spring elements 56 are arrangedcircumferentially about the rotational axis 22 in an annular array.Referring again to FIGS. 3 and 4, the spring elements 56 are alsoarranged radially between the seal shoes 54 and the seal base 52. Eachof the spring elements 56 is configured to connect a respective one ofthe seal shoes 54 with the seal base 52.

The spring element 56 shown in FIG. 4 includes first and second mounts82 and 84 (e.g., generally radial fingers/projections) and one or morespring beams 86 (e.g., cantilever-leaf springs). The first mount 82 isconnected to a respective one of the seal shoes 54 at (e.g., on,adjacent or proximate) the first circumferential side 66, where theopposing second circumferential side 68 of that seal shoe 54 is freefloating. The second mount 84 is connected to the seal base 52, and isgenerally circumferentially aligned with or near the secondcircumferential side 68.

The spring beams 86 are radially stacked and spaced apart with oneanother. Each of these spring beams 86 extends laterally (e.g.,tangentially or circumferentially relative to the rotational axis 22)between and is connected to the first mount 82 and the second mount 84.These the spring beams 86 may thereby laterally overlap a majorcircumferential portion (e.g., ˜65-95%) of the respective seal shoe 54.The spring beams 86 of the present disclosure, however, are not limitedto the foregoing exemplary configuration or values.

Referring now to FIG. 5, each of the spring beams 86 has a longitudinalcenterline 88, a length 90, a thickness 92 and a width 94 (see FIGS. 6and 7). The length 90 of the spring beam 86 extends longitudinally alongthe centerline 88 from the first mount 82 to the second mount 84.

The thickness 92 of the spring beam 86 extends radially between opposingradial side surfaces 96 and 98 of the spring beam 86. This thickness 92may be selectively varied/changed to provide at least a portion of thespring beam 86 with a radially tapered geometry. The thickness 92 of thespring beam 86 of FIG. 5, for example, is selectively varied/changed toprovide the spring beam 86 with opposing radially tapered end portions100 and 102 and an intermediate portion 104. The spring beam 86 of FIG.5 also includes opposing fillet portions 106 and 108.

The radially tapered geometry of each of the end portions 100 and 102 isdefined by a first distance 110 and a second distance 112. The firstdistance 110 is a radial distance that extends in a first radialdirection from the centerline 88 to the first radial side surface 96.The second distance 112 is a radial distance that extends in a secondradial direction opposite the first radial direction from the centerline88 to the second radial side surface 98.

The first and second distances 110 and 112 may be symmetricallydecreased as the respective end portion 100, 102 extends along thecenterline 88 towards the intermediate portion 104 such that thesurfaces 96 and 98 are substantially mirror images of one another alongthat end portion 100, 102. For example, the first and the seconddistances 110 and 112 may decrease according to the same function for atleast a part of the end portions 100, 102; e.g., each distance equals oris related to (e.g., half of) a square root of a longitudinal distancefrom a longitudinal mid-point 114 of the spring beam 86 (see graphicalrepresentation of FIG. 8). The first and the second radial side surfaces96 and 98 therefore substantially symmetrically converge toward oneanother and the centerline 88 as the respective end portion 100, 102extends along the centerline 88 towards the intermediate portion 104 andthe other end portion 102, 100. In this manner, a body of the springbeam 86 (including the fillets 116) may be symmetrical about thecenterline 88 and an associated mid plane of the spring beam 86. It isalso worth noting, at least part (or all) of the first and the secondsurfaces 96 and 98 along the end portions 100 and 102 shown in FIG. 5are convex. In contrast, fillets 116 between the surfaces 96, 98 and themounts 82, 94 are concave. Of course, at least some of the first and/orthe second surfaces 96 and 98 along the end portions 100 and 102 and/orother portions may also be concave.

In contrast to the end portions 100 and 102, the thickness 92 of thespring beam 86 in the intermediate portion 104 may be substantiallyconstant. The first and the second distances 110 and 112, in particular,may be substantially constant as the intermediate portion 104 extendsalong the centerline 88 between the end portions 100 and 102. Of course,in other embodiments, the first distance 110 or the second distance 112may be varied in order to provide shape (e.g., curvature) to the firstsurface or the second surface.

Referring to FIG. 6, the width 94 of the spring beam 86 extends axiallybetween opposing axial side surfaces 118 and 120 of the spring beam 86(see also FIG. 3). In this embodiment, the width 94 is substantiallyconstant across the entire length 90 of the spring beam 86. However, inother embodiments as shown in FIG. 7, the width 94 of the spring beam 86may be varied/change in a similar manner as described herein withrespect to the thickness 92 of the spring beam 86, or in a differentmanner. The spring beam 86 of FIG. 7, for example, includes opposingaxially tapered end portions 122 and 124 and an un-tapered intermediateportion 126. The spring beam 86 may also or alternatively include one ormore fillet portions 128 and 130, which provide one or more filletsbetween the spring beam 86 and one or more of the mounts 82 and 84.Furthermore, while the width 94 is described above with respect to FIG.7 as being tapered in addition to the tapered thickness 92, in otherembodiments the width 94 may be tapered and the thickness 92 may besubstantially constant.

Referring again to FIG. 5, the first end portion 100 is disposed next tothe first mount 82. This first end portion 100 has a longitudinal length132, which extends along the centerline 88 from the first fillet portion106 to the intermediate portion 104. The longitudinal length 132 is atleast about five percent (5%) of the length 90 of the spring beam 86. Inthe specific embodiment of FIG. 5, the longitudinal length 132 isgreater than about twenty-five percent (25%) of the length 90 of thespring beam 86; e.g., about 35-45% of the length 90. However, in otherembodiments, the longitudinal length 132 may be between about tenpercent (10%) and about twenty-five percent (25%) of the length 90 ofthe spring beam 86. In still other embodiments, the longitudinal length132 may be between about five percent (5%) and about ten percent (10%)of the length 90 of the spring beam 86. Of course, the presentdisclosure is not limited to the foregoing exemplary dimensions.

The second end portion 102 is disposed next to the second mount 84. Thissecond end portion 102 has a longitudinal length 134, which extendsalong the centerline 88 from the second fillet portion 108 to theintermediate portion 104. The longitudinal length 134 may besubstantially equal to (or different than) the longitudinal length 132.The longitudinal length 134 is at least about five percent (5%) of thelength 90 of the spring beam 86. In the specific embodiment of FIG. 5,the longitudinal length 134 is greater than about twenty-five percent(25%) of the length 90 of the spring beam 86; e.g., about 35-45% of thelength 90. However, in other embodiments, the longitudinal length 134may be between about ten percent (10%) and about twenty-five percent(25%) of the length 90 of the spring beam 86. In still otherembodiments, the longitudinal length 134 may be between about fivepercent (5%) and about ten percent (10%) of the length 90 of the springbeam 86. Of course, the present disclosure is not limited to theforegoing exemplary dimensions.

The intermediate portion 104 is disposed between the first end portion100 and the second end portion 102. This intermediate portion 104 has alongitudinal length 136, which extends along the centerline 88 betweenthe first end portion 100 and the second end portion 102. Thelongitudinal length 136 may be different than (or substantially equalto) the longitudinal lengths 132 and/or 134. The longitudinal length 136of FIG. 5, for example, is between about five percent (5%) and about tenpercent (10%) of the length 90 of the spring beam 86. However, in otherembodiments, the longitudinal length 136 may be between about tenpercent (10%) and about twenty-five percent (25%) of the length 90 ofthe spring beam 86. In still other embodiments, the longitudinal length136 may be between about twenty-five percent (25%) and about fiftypercent (50%) of the length 90 of the spring beam 86. Of course, thepresent disclosure is not limited to the foregoing exemplary dimensions.For example, the longitudinal length 136 may be larger than fiftypercent of the length 90 of the spring beam 86.

The first fillet portion 106 is disposed between the first end portion100 and the first mount 82. The first fillet portion 106 includes one ormore fillets 116. The first fillet 116 is disposed longitudinallybetween the first surface 96 and the first mount 82. The second fillet116 is disposed longitudinally between the second surface 98 and thefirst mount 82. Each of these fillets 116 may have a sectional geometrywhich provides or approximates curvature with G2 continuity at thetangency with the spring beam 86. Of course, in other embodiments, thefirst fillet portion 106 may be incorporated into the first end portion100.

The second fillet portion 108 is disposed between the second end portion102 and the second mount 84. The second fillet portion 108 includes oneor more fillets 116. The first fillet 116 is disposed longitudinallybetween the first surface 96 and the second mount 84. The second fillet116 is disposed longitudinally between the second surface 98 and thesecond mount 84. Each of these fillets 116 may have a sectional geometrywhich provides or approximates curvature with G2 continuity at thetangency with the spring beam 86. Of course, in other embodiments, thesecond fillet portion 108 may be incorporated into the second endportion 102.

The above-referenced dimensions of the spring beam 86 may be selected inorder to tailor a stress distribution within the spring beam 86. Inparticular, the first and the second distances 110 and 112 may be variedand the longitudinal lengths 132 and 134 may be selected in order touniformly distribute, or more uniformly distribute, stress along thespring beam 86. For example, FIG. 9 illustrates a left side of a tophalf portion of another spring beam 900 configured with a substantiallyconstant thickness except for within its fillet portions 902, one ofwhich is shown in FIG. 9. With such a configuration, the spring beam900/mount 904 are subject to concentrated stress loads at theintersection between the spring beam 900 and the mount 904. In contrast,referring to FIG. 10, by tapering the end region 100, 102 as describedabove and extending the longitudinal length 132, 134 (see FIG. 5) ofthat end region 100, 102 a relatively large percentage of the length 90of the spring beam 86, the stress load may be spread out more evenlyalong the spring beam 86. In this manner, the tapered configuration ofthe spring beam 86 may reduce and/or more evenly distribute internalstresses compared to the embodiment of FIG. 9.

Referring to FIG. 1, during operation of the primary seal device 40,rotation of the rotor structure 26 may develop aerodynamic forces andapply a fluid pressure to the seal shoes 54 causing the each seal shoe54 to respectively move radially relative to the seal land surface 38.The fluid velocity may increase as a gap between the seal shoe 54 andseal land surface 38 increases, thus reducing pressure in the gap anddrawing the seal shoe 54 radially inwardly toward the seal land surface38. As the gap closes, the velocity may decrease and the pressure mayincrease within the gap, thus, forcing the seal shoe 54 radiallyoutwardly from the seal land surface 38. The respective spring element56 may deflect and move with the seal shoe 54 to create a primary sealof the gap between the seal land surface 38 and ribs 80 withinpredetermined design tolerances.

While the primary seal device 40 is operable to generally seal theannular gap 30 between the stator structure 24 and the rotor structure26 as described above, fluid (e.g., gas) may still flow axially throughpassages 138 defined by radial gaps between the components 54, 56 and58. The secondary seal devices 42 therefore are provided to seal offthese passages 138 and, thereby, further and more completely seal theannular gap 30.

Each of the secondary seal devices 42 may be configured as a ring sealelement such as, but not limited to, a split ring. Alternatively, one ormore of the secondary seal devices 42 may be configured as a full hoopbody ring, an annular brush seal or any other suitable ring-type seal.

The secondary seal devices 42 of FIG. 1 are arranged together in anaxial stack. In this stack, each of the secondary seal devices 42axially engages (e.g., contacts) another adjacent one of the secondaryseal devices 42. The stack of the secondary seal devices 42 is arrangedwith the first ring structure 44, which positions and mounts thesecondary seal devices 42 with the stator structure 24 adjacent theprimary seal device 40. In this arrangement, the stack of the secondaryseal devices 42 is operable to axially engage and form a seal betweenthe end surface 76 of the array of the seal shoes 54 and an annularsurface 140 of the first ring structure 44. These surfaces 76 and 140are axially aligned with one another, which enables the stack of thesecondary seal devices 42 to slide radially against, but maintainsealingly engagement with, the end surface 76 as the seal shoes 54 moveradially relative to the seal land surface 38 as described above. Ofcourse, in other embodiments, the surfaces 76 and 140 may be misalignedwhere the secondary seal device(s) 42 are correspondingly configured.

The first ring structure 44 may include a secondary seal device supportring 142 and a retention ring 144. The support ring 142 is configuredwith an annular full hoop body, which extends circumferentially aroundthe rotational axis 22. The support ring 142 includes the annularsurface 140, and is disposed axially adjacent and engaged with the sealbase 52.

The retention ring 144 is configured with an annular full hoop body,which extends circumferentially around the rotational axis 22. Theretention ring 144 is disposed axially adjacent and engaged with thesupport ring 142, thereby capturing the stack of the secondary sealdevices 42 within an annular channel formed between the rings 142 and144. The stack of the secondary seal devices 42, of course, may also oralternatively be attached to one of the rings by, for example, a pressfit connection and/or otherwise.

The present disclosure is not limited to the exemplary primary sealdevice 40 type or configuration described above. Various othernon-contact seals are known in the art and may be reconfigured in lightof the disclosure above to be included with the assembly 20 of thepresent disclosure. Other examples of non-contact seals are disclosed inU.S. Pat. Nos. 8,172,232; 8,002,285; 7,896,352; 7,410,173; 7,182,345;and 6,428,009, each of which is hereby incorporated herein by referencein its entirety.

As described above, the assembly 20 of the present disclosure may beconfigured with various different types and configurations of rotationalequipment. FIG. 11 illustrates one such type and configuration of therotational equipment—a geared turbofan gas turbine engine 146. Such aturbine engine 146 includes various stator structures (e.g., bearingsupports, hubs, cases, etc.) as well as various rotor structures (e.g.,rotor disks, shafts, etc.) as described below, where the statorstructure 24 and the rotor structure 26 can respectively be configuredas anyone of the foregoing structures in the turbine engine 146 of FIG.11, or other structures not mentioned herein.

Referring still to FIG. 11, the turbine engine 146 extends along arotational axis 148 (e.g., the rotational axis 22) between an upstreamairflow inlet 150 and a downstream airflow exhaust 152. The turbineengine 146 includes a fan section 154, a compressor section 155, acombustor section 156 and a turbine section 157. The compressor section155 includes a low pressure compressor (LPC) section 155A and a highpressure compressor (HPC) section 155B. The turbine section 157 includesa high pressure turbine (HPT) section 157A and a low pressure turbine(LPT) section 157B.

The engine sections 154-157B are arranged sequentially along therotational axis 148 within an engine housing 160, a portion or componentof which may include or be connected to the stator structure 24. Thishousing 160 includes an inner case 162 (e.g., a core case) and an outercase 164 (e.g., a fan case). The inner case 162 may house one or more ofthe engine sections 155-157; e.g., an engine core. The outer case 164may house at least the fan section 154.

Each of the engine sections 154, 155A, 155B, 157A and 157B includes arespective rotor 166-170. Each of these rotors 166-170 includes aplurality of rotor blades arranged circumferentially around andconnected to one or more respective rotor disks. The rotor blades, forexample, may be formed integral with or mechanically fastened, welded,brazed, adhered and/or otherwise attached to the respective rotordisk(s).

The fan rotor 166 is connected to a gear train 172, for example, througha fan shaft 174. The gear train 172 and the LPC rotor 167 are connectedto and driven by the LPT rotor 170 through a low speed shaft 175. TheHPC rotor 168 is connected to and driven by the HPT rotor 169 through ahigh speed shaft 176. The shafts 174-176 are rotatably supported by aplurality of bearings 178; e.g., rolling element and/or thrust bearings.Each of these bearings 178 is connected to the engine housing 160 by atleast one stationary structure such as, for example, an annular supportstrut.

During operation, air enters the turbine engine 146 through the airflowinlet 150. This air is directed through the fan section 154 and into acore gas path 180 and a bypass gas path 182. The core gas path 180 flowssequentially through the engine sections 155-157. The bypass gas path182 flows away from the fan section 154 through a bypass duct, whichcircumscribes and bypasses the engine core. The air within the core gaspath 180 may be referred to as “core air”. The air within the bypass gaspath 182 may be referred to as “bypass air”.

The core air is compressed by the compressor rotors 167 and 168 anddirected into a combustion chamber 184 of a combustor in the combustorsection 156. Fuel is injected into the combustion chamber 184 and mixedwith the compressed core air to provide a fuel-air mixture. This fuelair mixture is ignited and combustion products thereof flow through andsequentially cause the turbine rotors 169 and 170 to rotate. Therotation of the turbine rotors 169 and 170 respectively drive rotationof the compressor rotors 168 and 167 and, thus, compression of the airreceived from a core airflow inlet. The rotation of the turbine rotor170 also drives rotation of the fan rotor 166, which propels bypass airthrough and out of the bypass gas path 182. The propulsion of the bypassair may account for a majority of thrust generated by the turbine engine146, e.g., more than seventy-five percent (75%) of engine thrust. Theturbine engine 146 of the present disclosure, however, is not limited tothe foregoing exemplary thrust ratio.

The assembly 20 may be included in various aircraft and industrialturbine engines other than the one described above as well as in othertypes of rotational equipment; e.g., wind turbines, water turbines,rotary engines, etc. The assembly 20, for example, may be included in ageared turbine engine where a gear train connects one or more shafts toone or more rotors in a fan section, a compressor section and/or anyother engine section. Alternatively, the assembly 20 may be included ina turbine engine configured without a gear train. The assembly 20 may beincluded in a geared or non-geared turbine engine configured with asingle spool, with two spools (e.g., see FIG. 11), or with more than twospools. The turbine engine may be configured as a turbofan engine, aturbojet engine, a propfan engine, a pusher fan engine or any other typeof turbine engine. The present invention therefore is not limited to anyparticular types or configurations of turbine engines or rotationalequipment.

While various embodiments of the present invention have been disclosed,it will be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible within the scope of theinvention. For example, the present invention as described hereinincludes several aspects and embodiments that include particularfeatures. Although these features may be described individually, it iswithin the scope of the present invention that some or all of thesefeatures may be combined with any one of the aspects and remain withinthe scope of the invention. Accordingly, the present invention is not tobe restricted except in light of the attached claims and theirequivalents.

What is claimed is:
 1. A non-contact seal assembly, comprising: a plurality of seal shoes arranged about an axis in an annular array, and comprising a first seal shoe; a seal base circumscribing the annular array of the seal shoes; and a plurality of spring elements comprising a first spring element; the first spring element radially between and connecting the first seal shoe and the seal base, and the first spring element comprising a spring beam having a length and a thickness; the length extending longitudinally along a centerline of the spring beam between opposing first and second ends of the spring beam; the thickness extending transversely to the centerline between opposing first and second surfaces of the spring beam; the first surface located a first distance from the centerline; the second surface located a second distance from the centerline; wherein the first distance and the second distance change as the spring beam extends longitudinally along the centerline such that the thickness of a portion of the spring beam tapers; and wherein the portion of the spring beam has a longitudinal length that is at least about five percent of the length of the spring beam.
 2. The non-contact seal assembly of claim 1, wherein the portion of the spring beam has a longitudinal length that is between about five percent and about ten percent of the length of the spring beam.
 3. The non-contact seal assembly of claim 1, wherein the portion of the spring beam has a longitudinal length that is between about ten percent and about twenty-five percent of the length of the spring beam.
 4. The non-contact seal assembly of claim 1, wherein the portion of the spring beam has a longitudinal length that is greater than about twenty-five percent of the length of the spring beam.
 5. The non-contact seal assembly of claim 1, further comprising a fillet longitudinally between the portion of the spring beam and a respective one of the first and the second mounts.
 6. The non-contact seal assembly of claim 1, wherein at least one of: the first surface is convex at least along a part of the portion of the spring beam; or the second surface is convex at least along a part of the portion of the spring beam.
 7. The non-contact seal assembly of claim 1, wherein the first distance and the second distance change, along at least a part of the portion of the spring beam, as a function of a square root of a longitudinal distance from a longitudinal mid-point of the spring beam.
 8. The non-contact seal assembly of claim 1, wherein: the portion of the spring beam is a first portion of the spring beam disposed longitudinally next to the first mount; the first distance and the second distance further change as the spring beam extends longitudinally along the centerline to provide a second portion of the spring beam, disposed longitudinally next to the second mount, with a tapered geometry; and wherein the second portion of the spring beam has a longitudinal length that is at least about five percent of the length of the spring beam.
 9. The non-contact seal assembly of claim 8, wherein the longitudinal length of the first portion of the spring beam is substantially equal to the longitudinal length of the second portion of the spring beam.
 10. The non-contact seal assembly of claim 8, wherein: an intermediate portion of the spring beam extends longitudinally between the first portion and the second portion of the spring beam; and at least one of the first distance or the second distance is substantially constant along the intermediate portion.
 11. The non-contact seal assembly of claim 10, wherein the intermediate portion of the spring beam has a longitudinal length that is between about five percent and about ten percent of the length of the spring beam.
 12. The non-contact seal assembly of claim 10, wherein the intermediate portion of the spring beam has a longitudinal length that is between about ten percent and about twenty-five percent of the length of the spring beam.
 13. The non-contact seal assembly of claim 10, wherein the intermediate portion of the spring beam has a longitudinal length that is between about twenty-five percent and about fifty percent of the length of the spring beam.
 14. The non-contact seal assembly of claim 1, wherein the portion of the spring beam has a tapered geometry, the spring beam extends radially relative to the axis between the first and the second surface, and the tapered geometry comprises a radial tapered geometry.
 15. The non-contact seal assembly of claim 1, wherein the portion of the spring beam has a tapered geometry, the spring beam extends axially relative to the axis between the first and the second surfaces, and the tapered geometry comprises an axial tapered geometry.
 16. The non-contact seal assembly of claim 1, wherein: the first spring element further includes a second spring beam extending a length longitudinally along a second centerline; the second spring beam includes opposing third and fourth surfaces; the third surface is disposed a third distance from the second centerline, and the fourth surface is disposed a fourth distance from the second centerline; the third and the fourth distances change as the second spring beam extends longitudinally along the second centerline to provide at least a portion of the second spring beam with a tapered geometry; and the portion of the second spring beam has a longitudinal length that is at least about five percent of the length of the second spring beam.
 17. The non-contact seal assembly of claim 1, further comprising: a ring structure axially engaged with the seal base; and a secondary seal device mounted with the ring structure and configured to substantially seal an annular gap between the ring structure and the annular array of the seal shoes.
 18. A non-contact seal assembly, comprising: a plurality of seal shoes arranged about an axis in an annular array and comprising a first seal shoe; a seal base circumscribing the annular array of the seal shoes; and a plurality of spring elements comprising a first spring element; the first spring element radially between the first seal shoe and the seal base, and comprising a spring beam; the spring beam extending a length longitudinally along a centerline between opposing ends of the spring beam, and the spring beam extending transversely to the centerline between a first surface and a second surface; wherein the first surface is a first distance from the centerline, and the second surface is a second distance from the centerline and opposite the first surface; and wherein the first surface and the second surface are convex along at least a portion of the spring beam, and the portion of the spring beam has a longitudinal length along the centerline that is at least five percent of the length of the spring beam.
 19. The non-contact seal assembly of claim 18, wherein the first distance and the second distance change as the spring beam extends longitudinally along the centerline to provide at least a portion of the spring beam with a tapered geometry.
 20. The non-contact seal assembly of claim 18, wherein the first spring element further comprises a first mount and a second mount; the first mount is connected to and is between the first seal shoe and a first of the opposing ends of the spring beam; and the second mount is connected to and is between the seal base and a second of the opposing ends of the spring beam. 